| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 268 |
26.6%
|
| 1 | Minor obstacle | 194 |
19.3%
|
| 2 | Moderate obstacle | 287 |
28.5%
|
| 3 | Major obstacle | 162 |
16.1%
|
| 4 | Very severe obstacle | 95 |
9.4%
|